The present invention relates to a process for the distillation of readily polymerizable vinyltoluene. More particularly, the present invention relates to a process for the distillation of vinyltoluene wherein the amount of said materials polymerized during distillation over an extended period of time is reduced.
It is well known that vinyltoluene polymerizes very readily, and furthermore, that the rate of polymerization increases at elevated temperatures. Since vinyltoluene produced by common industrial methods contains impurities, the vinyltoluene must be subjected to separation and purification processes in order to be suitable for most types of further industrial use. Such separation and purification is generally accomplished by distillation.
In order to prevent polymerization during distillation of vinyltoluene, various types of known polymerization inhibitors have been employed in connection with prior art distillation processes. Only a very few of these compounds have proved to be of any utility for inhibiting vinyltoluene polymerization under distillation conditions and even fewer are effective in the columns of the distillation apparatus.
In a typical distillation process for vinyltoluene, utilizing a polymerization inhibitor, the mixture of material to be distilled is generally contacted with the chemical polymerization inhibitor prior to distillation in the distillation apparatus. It remains as a significant problem today that the amount of polymer formed in the distillation apparatus is substantially higher than desired. Occasionally, polymer deposits accumulate inside the distillation apparatus until portions of the apparatus may become plugged or blocked.
Accordingly, there exists a strong need for a polymerization inhibitor which will effectively prevent the polymerization of vinyltoluene during distillation.